What
is the PERSIANN system?
The PERSIANN (Precipitation Estimation from Remotely Sensed
Information using Artificial Neural Networks) system uses
neural network function classification/approximation procedures
to compute an estimate of rainfall rate at each 0.25°
´ 0.25° pixel of the infrared brightness temperature
image provided by geostationary satellites. An adaptive
training feature facilitates updating of the network parameters
whenever independent estimates of rainfall are available.
The PERSIANN system (Hsu et al., 1997) was based on geostationary
infrared imagery and later extended (Hsu et al., 1999)
to include the use of both infrared and daytime visible
imagery. The PERSIANN algorithm used here is based on
the geostationary infrared imagery approach, while the
TMI 2A12 product provided by the TRMM satellite is used
for regular updating of the network parameters (Sorooshian
et al., 2000).
The
PERSIANN system rainfall product covers 50°S to 50°N
globally. The system uses grid infrared images of global
geosynchronous satellites (GOES-8, GOES-9/10, GMS-5, Metsat-6,
and Metsat-7) provided by NCDC, NOAA (Janowiak et al.,
2000), and TRMM TMI instantaneous rain product (2A12)
of NASA (kummerow et. al., 2000). The estimated PERSIANN
30-minute rain rates are aggregated to 6-hour accumulated
rainfall.
References
Hsu,
K., X. Gao, S. Sorooshian, and H.V. Gupta, 1997: Precipitation
estimation from remotely sensed information using artificial
neural networks, Journal of Applied Meteorology, Vol.
36, pp.1176-1190.
Hsu, K., H.V. Gupta, X. Gao, S. Sorooshian, "Estimation
of Physical Variables from Multi- Channel Remotely Sensed
Imagery Using a Neural Network: Application to Rainfall
Estimation," Water Resources Research, 35(5), 1605-1618,
1999.
Janowiak, J.E., R.J. Joyce, and Y. Yarosh, 2000: A real-time
global half-hourly pixel resolution infrared dataset and
its applications, Bulletin American Meteorology Society,
Vol. 82, pp. 205-217.
Kummerow, C., J. Simpson, O. Thiele, W. Barnes, A. T.
C. Chang, E. Stocker, R. F. Adler, A. Hou, R. Kakar, F.
Wentz, P. Ashcroft, T. Kozu, Y. Hong, K. Okamoto, T. Iguchi,
H. Kuroiwa, E. Im, Z. Haddad, G. Huffman, B. Ferrier,
W. S. Olson, E. Zipser, E. A. Smith, T. T. Wilheit, G.
North, T. Krishnamurti, K. Nakamura, 2000: The Status
of the Tropical Rainfall Measuring Mission (TRMM) after
Two Years in Orbit. Journal of Applied Meteorology: Vol.
39, No. 12, pp. 1965-1982.
Sorooshian, S., K. Hsu, X. Gao, H.V. Gupta, B. Imam, and
D. Braithwaite, 2000: Evaluation of PERSIANN system satellite-based
estimates of tropical rainfall, Bulletin American Meteorology
Society, Vol. 81, pp. 2035-2046.
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